serializing array when nested with other attributes in rails 5 - ruby-on-rails

Question

I have a ruby (2.4.0p0) rails (5.0.2) controller from which I wish to return a json result containing a list of Thing objects as well as some high level info (such as next and previous from Kaminari paging).
Consider a Thing with an association to Owner. Thing has a owner_id attribute.
For #things = Thing.page(1).per(2) I will be able to use
render json: #things
and get;
[
{ "id": 1, "owner_id": 1, "name": "thing1" },
{ "id": 2, "owner_id": 1, "name": "thing2" }
]
Good. If I then create a serializer called ThingSerializer.rb and define owner such that it adds "owner":"CatInHat" instead of "owner_id":1
This works as well;
[
{ "id": 1, "owner": "CatInHat", "name": "thing1" },
{ "id": 2, "owner": "CatInHat", "name": "thing2" }
]
This is good, but, my problem comes when I want to add higher level data and label the list as "results" such as when I try;
render json: { next:"some_url_link",previous:"some_other_url_link", results: #bags}
I'd like to get;
{ "next":some_url_link,
"prev":some_other_url_link,
"results":[ { "id": 1, "owner": "CatInHat", "name": "thing1" }, { "id": 2, "owner": "CatInHat", "name": "thing2" } ]
}
What I get is nearly the above but with "owner_id":1 instead of "owner":"CatInHat" - my serializer does not seem to be used when I label and nest my list of things. What is the appropriate way to use my serializer and get this output?
If I create config/initializers/active_model_serializers.rb and add
ActiveModel::Serializer.config.adapter = :json_api
It gives me an api which is similar but I don't know if it can be customized to fit the spec I need above.
thank you for any help

Answer 1

It looks like the serialization logic in render json: ... only kicks in if the attribute is an ActiveRecord object or an array of ActiveRecord objects. Since you are giving it a hash, it will not inspect the individual attributes and recursively apply the serializers.
You can try manually applying ThingSerializer:
render json: {
next: ...,
prev: ...,
results: #things.map { |thing|
ThingSerializer.new(thing).attributes
},
}